Welcome to the Cake Decorators Q&A

asked December 20th 2018

Cake blow out.

Hi, I just made a shoebox, style cake, used Italian meringue buttercream for the filling, and made chocolate ganache. For the outer sides. I used Nestle plaistow 45% dark chocolate and made it with less cram as it is quite hot here. I ganached the cake and put it in the refrigerator overnight. Took it out to cover it with fondant. It was about 30 degrees here in Sydney. The ganache was sweating a lot. Dabbed it with paper towels , then covered with fondant,
kept cake in front of the fan as I don't have AC and about 1hour later there is this huge blow out, from the side that was facing the fan. What did I do wrong. Please help as the whole cake is ruined, and there is sagging fondant on all sides. Thanks


Hi qvkake

Unfortunately this happens quite a lot in very hot conditions . It's to do with temperature changes from fridge to room temperature. The sweating is the coldness of the cake hitting the heat of the room and the blow out is probably to do with the meringue buttercream melting and oouzing out of the sides.

The best thing to do is try and remove the fondant as best as you can. Make a fresh batch of ganache using 3:1 ration or even 4:1 ratio so it's nice and strong. To repair the filling, try and lift the layers off with a warmed palette knife and scrape off as much of the filling as possible and tidy up the layers. I would recommend making a strong white ganache dam about an inch in from the edge of each layer to contain the filling. Let the dam set first before filling. Once filled, place a disc of parchment paper on the cake and place a weight or plate on top to help settle the filling. Store in the fridge until it is stable before re ganaching. Allow the ganached cake to dry before icing.

Personally I would avoid meringue based buttercream in favour of white chocolate ganache buttercream. However, if you still want to use the IMB, try not to over fill the layers. Take a peek at similar problems and solutions here:


I hope you can salvage the cake. It's such a pain when this happens. I know what it's like asI've had to do the same in the past. You might want to redo it if you think it's too much work??
Good luck, let me know how you get on please. X 🙂


Thanks for your help. I think, you are right, I had put a lot more filling of the IMBC, but I had used the Nestle dark 45% chocolate for the ganache. I will reduce the cream further in the future for a hot day. I could not redo the covering of fondant, as it would entail too much work, and I did not have enough supplies.

Also do you have a reliable recipe for the white chocolate ganache buttercream. You mentioned that I make a dam of white chocolate ganache . So is white chocolate ganache going to be firmer and safer than dark chocolate ganache.


Hi qvkake

You can add cooled melted white chocolate to the IMBC or use butter icing with added white chocolate. I use the following recipe which can be made in mulitples and used only for filling. One batch is suffcient for filling a three layer eight inch cake:

100g melted white chocolate
140g unsalted butter
70g icing sugar
2 tea spoons vanilla extract

Cream butter and icing sugar until very white
Add vanilla
Add cooled white chocolate
Beat until very creamy

or you could try this one:

White Chocolate Buttercream

For a strong white ganache use 4 times chocolate to 1 times cream ratio. This will make a strong dam and also good for covering. White ganache is not as strong as dark but both can be made stronger by increasing the chocolate to cream ratio.

I understand that you used 45% cocoa content chocolate. This would be more than sufficient in normal heat conditions but as you are experiencing extreme heat, it will help if you increase the chocolate amount rather than reducing the cream..... or use a higher cocoa content 50% - 60% for dark and up to 32% for white. Both types of ganache are safe and should be made up according to climatic conditions. Increasing the chocolate ratio will make ganache stronger.

I'm just so sorry that you have had this bad experience. I hope your next project yields better result. X